Trench Grates Glossary

An overview of terminology used to describe trench grates

This glossary provides a list of terms and definitions for trench grates. It can be used as a helpful guide when reading about hardscapes or when installing trench grates.

Reliance Foundry trench grates offer rapid and reliable drainage solutions for a variety of spaces ranging from urban areas to industrial environments. They prevent any flooding by efficiently removing excess surface water, ensuring that the area remains dry and safe for pedestrian and vehicular traffic.

Trench grate terms

Debris chute

A debris chute is a sloping channel that allows the debris that falls into the bolt holes of the trench grate’s frame to pass through to the trench below. This prevents premature failure of bolted trenches due to debris collecting in the bolt holes during installation and preventing the bolt from turning down completely.

Debris chute on trench grate
Debris chutes allow debris in the bolt holes to harmlessly pass through to the trench below during installation.

Expansion joint

An expansion joint allows for the thermal expansion of joined metal parts without causing distortion. It also allows materials to absorb vibration in the event of ground settlement or earthquakes.

Gray cast iron

Gray cast iron is a type of cast iron with a graphitic microstructure. It conforms to ASTM A-48, Class 35 or higher. Gray cast iron experiences less shrinkage than other ferrous metals, has high corrosion resistance, and good machinability. It is a durable material for manufacturing high-quality trench grates.


Hardscape includes the inorganic built elements in a landscape, including concrete, metal, glass, or stone. Walkways, driveways, walls, and stairs are the most common examples, yet hardscape can also be ornate and decorative, or it can be functional to enhance the horticultural elements. It is installed to protect greenspace, provide drainage, and improve accessibility.

Heavy-duty trench grates

Heavy-duty trench grates must exceed proof loads of 16,000 lbs (H-20 load rating). Reliance Foundry trench grates are safe for heavy-duty use.

Steel rebar

Steel rebar is steel rod reinforcement in concrete. When installing trench grates, rebars are bent 90 degrees to anchor the trench grates securely in concrete.

Seat form

Seat form is a piece of wood used during installation to adjust the position of the trench grate frame so that it is at the proper elevation with the trench form.

Trench forms

Trench forms are materials, such as wood, used to construct a temporary mold into which concrete is poured.

Trench grate

Trenches are a type of drainage system containing a dominant trough or channel-shaped body and are used for the rapid evacuation of surface liquids. Trench grates are the grates placed over the trenches to keep out large debris and remove tripping hazards and obstacles for traffic. Trenches are useful in any open space that has the potential to collect surface water, such as parking lots, sidewalks, and loading docks.